DECORATIVE TREATMENT OF AN ARBORETUM. 327 



liberal allowance of space, but also become the princi 

 ])al objects on account of their breadth and altitude 

 Tliey are mostly to be found in Alliances 3, 4, 7, 12 

 13, 22, 24, 2G. In distributing them on the ground 

 their groups, of whatever rank they may be — i. e 

 whether generic^ ordinal^ or allied — should be so 

 managed as not only to be in requisite union with the 

 cognate families of humbler growth, but also to be- 

 come the leading and most conspicuous features of 

 the scene. Where this expedient is properly employed, 

 it will add much variety to the whole, and will pro- 

 duce a greatly superior effect to that attained by a 

 mere botanical succession, or by the intermingling of 

 many genera in the same group, or where the place 

 assigned to each plant is determined by its stature, and 

 not by' its generic character. Though we disapprove 

 of the intermingling of genera with each other, we 

 hold that many of tliem may be put in juxtaposition. 

 There are even certain alliances in whicli the numbers 

 of genera and sj)ecies are so limited that they may 

 very properly form combined groups, as in the follow- 

 ing associated pairs: 8-9, 10-11, 19-20, 27-28, 29-30. 

 Between the different groups of trees and shrubs, 

 lawns of varying breadth should be interposed ; the 

 broader lawns being partly occupied witli clumps of 

 low-growing trees and shrubs, and the narrower glades 

 being left entirely open. The distance at which the 

 trees and shrubs should be planted in their respective 

 groups must depend on tlie magnitude M'hich the indi- 

 vidual species acquire in this country. Wliile there 

 should be space for a pretty full development of each, 

 they should, generally speaking, not be placed at sucli 

 distances apart as to prevent various members of the 



